Fiber Distributed Data Interface (FDDI) connectors are used for data transmission in, among other things, computer systems and particularly local area networks. Typical FDDI connectors include a connector body having an entrance at one end for receiving a fiber optic cable. The fiber optic cable breaks out inside the connector body into two separate optical fibers that are attached to, and terminate in, two ferrules. The connector body mates with one of several different receptacles including, for example, an active device receptacle, a transceiver adaptor, a dual ST-coupling, or an FDDI to FDDI coupling.
The receptacles typically include a spline cooperating with a connector key or polarizing element to ensure that the particular receptacle being used is compatible with the mated connector. See U.S. Pat. No. 5,166,995 to Weber, the teachings of which are specifically incorporated herein by reference. There are generally four basic keying formats in the American National Standards Institute (ANSI) protocol, that is the A, B, M ("Master")and S ("Slave") polarizations as disclosed in FDDI:X3.166-1990; ISO/IEC 9314-3 and X3T9.5/88-155 the teachings of which are hereby incorporated by reference. The polarizations are achieved by the size and placement the spline in the cooperating receptacle. For example, a connector polarized in the S configuration has a centrally disposed full width channel. The "A" polarization is a partial width channel located to the right of center, while the "B" polarization is a partial width channel located to the left of center. The "M" polarization is a partial width channel located at the center of the connector.
In order to avoid molding different connector bodies to accommodate the four different polarization possibilities, prior connectors have been designed with three separate and different keying elements that fit into the connector to configure the connector to the desired polarization. The connector housing itself has a full width central channel for the S polarization. To configure the connector to the A, B, or M polarizations, a polarizing key having an appropriately sized and placed channel is placed in the full width channel in the connector body. See, for example, U.S. Pat. No. 4,979,792, Weber et al. the teachings of which are incorporated herein by reference.
The keying system disclosed in the Weber patent requires multiple keys for each connector kit. In order to accommodate the possibility of changing connector polarizations, multiple unused keys must be retained together with the associated connector. See for example U.S. Pat. No. 4,979,792 to Weber et al. Keying systems having a single keying element for each polarization obviate the need to retain multiple unused parts. Single keys tend to be small making them difficult to manipulate. There is a need, therefore, for a single key polarization system that is easily manipulated for changing polarization modes.